Silver halide photographic material containing azo masking couplers

ABSTRACT

A light sensitive color photographic material having at least one silver halide emulsion layer which contains a red azo masking coupler of the following formula: WHEREIN R1, R2, R3 and R4 are as defined in the description, which red cyan coupler has advantageous properties with respect to suitable absorption dyes, efficient emulsifiability and excellent reactivity.

United States Patent Puschel et al.

[ Oct. 29, 1974 1 SILVER HALIDE PHOTOGRAPHIC MATERIAL CONTAINING AZOMASKING COUPLERS [75] Inventors: Walter Puschel, Leverkusen,

Germany; Gaston Jacob Benoy, Edegem, Belgium; Dietmar Kalz, Koeln,Germany [73] Assignee: Agta-Gevaert Aktiengesellschaft,

Leverkusen, Germany [22] Filed: May 4, 1972 21 Appl. No.: 250,300

[30] Foreign Application Priority Data May 7, 1971 Germany 2122570 [52]US. Cl. 96/100, 96/9 [51] Int. Cl G03c 1/40 [58] Field of Search 96/100,9, 56.1

[56] References Cited UNITED STATES PATENTS 3,459,552 8/1969 Yoshida etal. 96/100 3,556,796 l/1971 Eynde et al 96/9 3,615,225 10/1971 Otto etal 96/100 3,676,142 7/1972 Carpentier et al 96/9 Primary Examiner-J.Travis Brown Attorney, Agent, or Firm-Connolly and Hultz [5 7 ABSTRACT Alight sensitive color photographic material having at least one silverhalide emulsion layer which contains a red 2120 masking coupler of thefollowing formula:

OH S OzNH-Rl wherein R R R and R are as defined in the description,which red cyan coupler has advantageous properties with respect tosuitable absorption dyes, efficient emulsifiability and excellentreactivity.

5 Claims, No Drawings SILVER IIALIDE PIIOTOGRAPHIC MATERIAL CONTAININGAZO MASKING COUPLERS The invention relates to a color photographicmaterial with improved color reproduction which contains red cyancouplers for the production of so-called builtin masks, preferably in anemulsified form.

It is known that the unwanted side color densities of the image dyesproduced by chromogenic development of multilayered color photographicmaterials can be eliminated by masking processes. This may be achievedby using so-called built-in masks in color photographic materials. Thesemasks may be produced, for example, in the course of the photographicprocess, by using socalled masking couplers which have a color whichmasks the unwanted side color densities of the image dyes. Colorcouplers suitable for this purpose generally have the same chemicalstructure as ordinary color couplers but at the point of coupling forthe reaction with the oxidized color developer they contain a group,generally an azo dye group, which imparts to the color coupler the colorwhich is split off in the reaction with the oxidized color developer. Inthe process of color development, the image dye is formed in the exposedand developed areas while in the unexposed areas the color of thecolored coupler used is preserved. Ideally, the gradation of unwantedside densities obtained in the course of processing is compensated by anequal but opposite gradation of the masking dye so that the density inthe unwanted region of the spectrum is uniform regardless of theconditions of exposure. In an efficiently masked cyan coupler, forexample, the yellow and magenta side densities measured behind colorfilters after processing are constant and independent of the conditionsof exposure.

The azo masking couplers mentioned above may either be emulsified in thephotographic layers or introduced in the form of aqueous alkalinesolutions. It is frequently observed that the coupling activity ofhydrophobic emulsified couplers is less than that of hydrophiliccouplers dissolved in an aqueous alkaline solvent. If, however, attemptsare made to render such couplers envisaged for the emulsificationprocess more hydrophilic by introducing suitable substituents,difficulties arise in the emulsification process. This causes the choiceof substituents to be severely restricted. The choice is still furtherreduced by the necessity of keeping the dyes used within a suitableabsorption range for masking the cyan side densities.

It is an object of the invention to find red azo masking couplers whichare sufficiently hydrophobic to ensure that they can be efficientlyemulsified but are sufficiently hydrophilic to enable the couplingreaction in the layer to take place sufficiently rapidly; furthermore,the absorption maximum should be situated so that the side densities ofthe cyan partial image are masked as completely as possible.

It now has been found a light sensitive color photographic materialhaving at least one silver halide emulsion layer which contains a redcyan coupler of the following formula:

wherein A Rf, R or R represent hydrogen or alkyl with up to 18 carbonatoms, these groups being either the same or different, at least one ofthese groups being an alkyl radical with preferably 12 to 18 carbonatoms which renders the compound resistant to diffusion;

R represents alkyl with four to seven carbon atoms, or cycloalkyl suchas cyclohexyl which may contain other substituents, e.g. alkylpreferably with up to five carbon atoms, especially methyl.

The following compounds have proved to be especially suitable:

(1) (|)H I SOz-NHCH o ONH -OHa liaHu N ii N l -0 (2) I s OH S O:|'NHCH3C O NH III-CH3 l CraHar N ll N H/ CH3 (3) S Qz-NH-CrsHflr @woo -oiunCompound 4 is a mixture of isomers. The compounds according to theinvention are prepared according to methods known in the literature bydiazotising the corresponding amines and coupling with naphtholcarboxylic acid anilide s. Compound 5 of the table of formulae, forexample is prepared as follows:

2.9 g of anthranilic acid cyclohexyl ester are dissolved in 4 ml ofcone. hydrochloric acid and ml of water with heating, then'cooled to 0 Cand diazotised by the addition of a solution of 0.85 g of sodium nitritein 3 ml of water. The reaction mixture is then stirred for 1 hour, theexcess of nitrite is destroyed and the pH is adjusted to 6-7. Theproduct is then coupled with 6 g of the corresponding coupling componentdissolved in l0 ml of pyridine with the addition of ml of water and 2 mlof cone. sodium hydroxide solution. The pH should be maintained at about12 during the coupling reaction. After 15 minutes, the reaction mixtureis adjusted to pH 7 with glacial acetic acid and the slimy precipitateformed is taken up in methylene chloride which is then dried with sodiumsulfate and the residue is concentrated by evaporation. The product ispurified by recrystallizing from ethyl acetate.

The new red azo masking couplers are superior to the corresponding knowncouplers in many of their properties. They are red to magenta in color,having an absorption maximum between 450 and 510 nm. This absorptionrange satisfies the requirement that both the blue and the greenabsorption range of the cyan coupling dyes formed should be effectivelymasked. Another advantage of the couplers is that due to the combinationof esters of aliphatic alcohols which have a medium number of carbonatoms with a sulfonamide group in the'same molecule the couplers areespecially advantageous in three of their properties: Suitableabsorption of dyes, efficient emulsifiability and excellent reactivity.

The masking couplers to be used according to the invention may be usedeither alone of preferably together with colorless cyan couplers incolor photographic silver halide emulsions, especially in'layers whichare sensitized to red light.

The masking couplers are preferably incorporated in an emulsified formwith the silver halide emulsion.

The compound is dissolved in known manner in suitable organic solvents,e.g. in esters of aliphatic carboxylic acids, especially in ethylacetate, and this solution a is emulsified in the silver halide emulsionwhich is ready for casting. According to another method of carrying outthis process, so-called crystalloids, that is to say high boilingsolvents, e.g. tricresyl phosphate or dibutylphthalate, may be added tothe coupler. If the new substances are used together with colorless cyancouplers, the substances may be added to the light sensitive silverhalide emulsions either successively or together from a common solution.The method of addition to the emulsion is not critical. and the mostsuitable method can easily be determined by simple tests.

The required dye emulsions may be prepared, for example, as follows:

0.25 g of a fatty alcohol sulfonate per 100 g of gelatin solution isadded as emulsifier to a 7.5 percent solution of a photographic gelatin.

The required quantity of dye is then dissolved in 3 to 5 times itsquantity of ethyl acetate and this solution is run into a gelatinsolution heated to 50 C, using a Kotthoff stirrer. The emulsificationtime is 5 to 15 minutes, depending on the quantity. Any ethyl acetatestill present is removed under vacuum. The emulsion is then ready foruse. If necessary, 10 to 100 percent of an oil forming substance such asdibutylphthalate, the amount being preferably based on the quantity ofdye per kg:

used, may be added to the dye solution before emulsification.

The light sensitive emulsions may contain silver chloride, silverbromide or mixtures thereof, or with a small iodide content of up tomols percent. The binders used may be the usual hydrophilic binders suchas proteins, especially gelatin, polyvinyl alcohol, polyvinylpyrrolidone, cellulose derivatives such as carboxymethylcellulose orderivatives of alginic acid.

The emulsions may also contain the usual derivatives, e.g. optical orchemical sensitizers, stabilizers, hardeners, and plasticizers.

Any color forming developers which contain a primary amino group may beused for development. It is preferred to use those of theparaphenylenediamine series, e.g. N,N-diethyl-para-phenylenediamine, 2-amino-5-diethylaminotoluene-N-butyl-N-w-sulfobutylparaphenylenediamine,2-amino-5-(N-ethyl-N-B- methanesulfonamidoethylamino)toluene, and 2-amino-S-N-ethyl-N-hydroxyethylaminotoluene.

The following Examples illustrate the invention:

EXAMPLE 1 3.2 g of the red masking coupler 6 in that table of formulaeare dissolved in ml of ethyl acetate and then emulsified in 250 g of a7.5 percent gelatin solution. The emulsion is mixed with 100 g of silverbromide gelatin emulsion (50 g of silver in the form of silver halideper kg) with stirring and diluted with 1 200 ml of water. To thisemulsion mixture are added 15 ml of a 10 percent aqueous saponinsolution and 5 ml of a 0.5 percent aqueous chrome acetate solution andthe emulsion is then cast on. a layer support of cellulose triacetate.Thickness of layer 5 After drying, the film is exposed behind a greystep wedge and developed for 6 minutes in a developer of the followingcomposition:

2.5 g of N.N-diethyl-p-phenylenediamine sulphate 2 g of sodium sulfite lg of potassium bromide 25 g of potassium carbonate 0.5 g ofhydroxylamine sulfate Water up to 1 litre.

After bleaching and fixing in the usual baths, a cyan colour wedge withvery efficiently masked yellow and red side densities is obtained.

EXAMPLE 2 2.5 g of the cyan coupler of the following formula are addedin the form of a gelatin dispersion together with 0.25 g ofdibutylphthalate, as oil forming agent, to 100 g of a red-sensitizedsilver bromide gelatin emulsion which contains 70 g of silver in theform of silver halide aiin 1.7 g of masking coupler 3, also dispersed ingelatin, are then added.

15 ml of a 10 percent aqueous saponin solution and 5 ml of a 0.5 percentaqueous chrome acetate solution are then added to this emulsion mixtureand the mixture is cast on 10 m of a layer support of cellulosetriacetate. The thickness of the layer is 4 pm.

After drying, the material is exposed behind a grey step wedge anddeveloped in a developer of the following composition:

5 g of 2-amino-5-(N-ethyl-N-B-methane sulfonamidoethylamino)-toluene 4ml of benzyl alcohol 2.5 g of sodium hexametaphosphate 2.0 g of sodiumsulfite sicc.

1.0 g of sodium bromide 0.5 g of sodium hydroxide 50 g of Na2CO3.H O

Water up to l litre.

After carrying out the other usual color photographic processesinvolving bleaching and fixing, a cyan colour is obtained in which theyellow and the magenta side densities of the cyan dye formed isefficiently masked. The masking effect is considerably better than thatobtained with known red cyan couplers. Similar results are obtained whenusing a silver iodobromide emulsion which contains g of silver in theform of silver halide and which contains, for every g of emulsion, l gof theabove mentioned cyan coupler and 0.65 g of masking coupler 3, alsoin an emulsified form.

The excellent effect of the masking couplers used according to theinvention is also manifested when using other cyan couplers incombination with, these masking couplers. Thus, for example equally goodresults are obtained in the silver halide emulsion mentioned above whenthe cyan coupler is replaced by couplers of the following formulae:

R 300ml (CH1) 4-0 s'daiiiit'i" V O 0 UPI-O R4 in which R,, R or Rrepresents hydrogen or alkyl with upto 18 carbon atoms, these groupsbeing either the same or different, at least one of these groups beingan alkyl radical which renders the compound resistant to diffusion andrepresents alkyl having four to seven carbon atoms or cycloalkyl.

2. A material as claimed in claim 1 in which R R and R represents alkyland one of R R or R,-, is an alkyl radical with 12 to l8 carbon atoms.

3. A material as claimed in claim I in which the red cyan couplers areincorporated in the silver halide emulsion layer in an emulsified form.

4. A material as claimed in claim 3 in which 10 to percent, based on thequantity of dye used, of dibutylphthalate is added to the dye solutionbefore emulsification.

5. A material as claimed in claim 1 containing in the silver halideemulsion layer in addition colorless cyan coupler selected from thegroup consisting of cyan couplers of the phenol or naphthol series.

73,713" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQ Patent No.5 Dated O tober 2Q, 1071;

Inventor(s) Walter SChel eta1 It is certified that error appears in theabove-identified patent. and. that said Letters Patent arevherebycorrected as shown below:

Column 8, claim l, line iz i'sfert R before "represents".

Signed and [sealed this 18th day of March 1975.

- (SEAL) Attest:

c. MARSHALL DANN- -RUTH C. MASON v Commissioner of Patents AttestingOfficer and Trademarks

1. A LIGHT SENSITIVE COLOR PHOTOGRAPHIC MATERIAL HAVING AT LEAST ONESILVER HALIDE EMULSION LAYER WHICH CONTAINS A RED CYAN COUPLER, WHICHCYAN COUPLER IS OF THE FOLLOWING GENERAL FORMULA:
 2. A material asclaimed in claim 1 in which R1, R2 and R3 represents alkyl and one ofR1, R2 or R3 is an alkyl radical with 12 to 18 carbon atoms.
 3. Amaterial as claimed in claim 1 in which the red cyan couplers areincorporated in the silver halide emulsion layer in an emulsified form.4. A material as claimed in claim 3 in which 10 to 100 percent, based onthe quantity of dye used, of dibutylphthalate is added to the dyesolution before emulsification.
 5. A material as claimed in claim 1containing in the silver halide emulsion layer in addition colorlesscyan coupler selected from the group consisting of cyan couplers of thephenol or naphthol series.